Silicate weathering in anoxic marine sediment as a requirement for authigenic carbonate burial
Journal Article
·
· Earth-Science Reviews
- Oregon State Univ., Corvallis, OR (United States); OSTI
- Geological Survey of Norway, Trondheim (Norway)
- Univ. of Washington, Seattle, WA (United States)
- Univ. of Texas, Austin, TX (United States)
- Korea Inst. of Geoscience and Mineral Resources, Daejeon (Korea, Republic of)
- Northern Arizona Univ., Flagstaff, AZ (United States)
- Wilhelms-Univ. Münster (Germany)
- IFM-GEOMAR Leibniz Inst. of Marine Sciences, Kiel (Germany)
We emphasize the importance of marine silicate weathering (MSiW) reactions in anoxic sediment as fundamental in generating alkalinity and cations needed for carbonate precipitation and preservation along continental margins. We use a model that couples thermodynamics with aqueous geochemistry to show that the CO2 released during methanogenesis results in a drop in pH to 6.0; unless these protons are buffered by MSiW, carbonate minerals will dissolve. We present data from two regions: the India passive margin and the active subduction zone off Japan, where ash and/or rivers supply the reactive silicate phase, as reflected in strontium isotope data. Offshore India and Korea, alteration of continent-derived silicates results in pore water enriched in radiogenic 87Sr, with 87Sr/86Sr ratios as high as 0.7095 and 0.7104, respectively. Off Japan, strontium in pore water influenced by ash alteration is depleted in 87Sr, with 87Sr/86Sr as low as 0.7065. Carbonate minerals formed by alkalinity and cations generated through MSiW carry these strontium isotopic signals, and are typically dolomite, siderite, and Fe-rich calcite. These contrast with the aragonite and high-magnesium calcite that form during anaerobic oxidation of methane and incorporate the coeval seawater 87Sr/86Sr signal. We show that MSiW is necessary for authigenic carbonate formation and preservation along continental margins, which remove carbon from Earth’s surface at rates previously estimated to be at least 1012 mol yr-1. In addition, these authigenic carbonates are of relevance to studies of the deep biosphere, fluid flow, seismogenesis, slope stability, and reservoir characteristics.
- Research Organization:
- Oregon State Univ., Corvallis, OR (United States)
- Sponsoring Organization:
- USDOE Office of Fossil Energy (FE)
- Grant/Contract Number:
- FE0013531
- OSTI ID:
- 1799759
- Journal Information:
- Earth-Science Reviews, Journal Name: Earth-Science Reviews Vol. 200; ISSN 0012-8252
- Publisher:
- ElsevierCopyright Statement
- Country of Publication:
- United States
- Language:
- English
Similar Records
Cementation and diagenetic fluid mixing in South Brae oil field, North Sea, U. K
Open system diagenesis and the los of provenance signatures: isotopic and elemental data from sandstones, Frio Formation, south Texas
Strontium isotopic stratigraphy utilizing authigenic dolomites in hemipelagic sediments
Conference
·
Tue May 01 00:00:00 EDT 1990
· AAPG Bulletin (American Association of Petroleum Geologists); (USA)
·
OSTI ID:6688353
Open system diagenesis and the los of provenance signatures: isotopic and elemental data from sandstones, Frio Formation, south Texas
Conference
·
Tue May 01 00:00:00 EDT 1990
· AAPG Bulletin (American Association of Petroleum Geologists); (USA)
·
OSTI ID:6677334
Strontium isotopic stratigraphy utilizing authigenic dolomites in hemipelagic sediments
Conference
·
Tue May 01 00:00:00 EDT 1990
· AAPG Bulletin (American Association of Petroleum Geologists); (USA)
·
OSTI ID:6720920